CN101627320A

CN101627320A - Detector head proximity sensing and collision avoidance apparatuses and method

Info

Publication number: CN101627320A
Application number: CN200780042886A
Authority: CN
Inventors: R·C·丹布罗西奥; R·J·阿斯杰斯; H·贝特尔森; G·A·德福柯尔特; M·J·彼得里洛; A·柯尔祖欣; S·鲁比奥; S·D·希夫纳; P·L·帕蒂诺; A·P·罗默斯
Original assignee: Koninklijke Philips Electronics NV
Current assignee: Koninklijke Philips NV
Priority date: 2006-11-20
Filing date: 2007-10-31
Publication date: 2010-01-13
Also published as: JP5457834B2; WO2008063835A2; CN104983438A; WO2008063835A3; EP2087373B1; US20100061509A1; US8269176B2; JP2010510490A; EP2087373A2; CN104983438B

Abstract

A kind of gamma camera (8,180) comprises at least one radiation detector head (10,12,210,212).At least one this radiation detector head (10,12,210,212) comprises a plurality of capacity cells (60,260,76,276) on the radiosensitive part (50) that is arranged on this radiation detector head at least.Proximity sensor monitor (62) is coupled with described a plurality of capacity cells so that detect the degree of approach of experimenter and radiation detector head based on the measurement electrical characteristics of capacity cell.Collision sensor monitor (64) and described a plurality of capacity cell are coupled so that detect the conduction current that flows between the spaced apart parallel current-carrying plate (66,67) of capacity cell in response to the mechanically deform at the interval between the plate.

Description

Detector head proximity sensing and collision avoidance apparatuses and method

The present invention relates to imaging, test, diagnosis and association area.The present invention is particularly useful for gamma camera, comprises the medical image system of gamma camera, utilizes the tomography medical imaging method of gamma camera etc., and by specifically present invention is described with reference to these aspects.Yet the present invention more generally is applicable to the removable detector head of basic any kind, and the imaging system and the formation method that adopt this removable detector head.

In nuclear medicine imaging technique such as single photon emission computed tomography (SPECT), experimenter's (such as the mankind or animal patient, the mankind or animal test subject etc.) is bestowed the radiopharmaceutical that comprises radioactive isotope or other radioactive components.This radiopharmaceutical randomly is configured to assemble in specific tissue or organ (such as blood, skeletal tissue, liver, brain etc.).Because radioactive isotope or other radioelement have some toxicity to the experimenter, advantageously keep low radiopharmaceutical dosage at the live body experimenter.The signal that is produced by the radiopharmaceutical of being bestowed is correspondingly lower, therefore pays special attention to radiation detector sensitivity.

Being used for making during imaging sequence the maximized a kind of technology of radiation detector sensitivity is to adopt suitable shape tomographic trajectory, and wherein detector head moves to keep the distance of little detector head to the patient towards the patient or away from the patient during advancing.Yet, detector head is fragile, relatively large (in some gamma camera relatively, each detector head has the radiation-sensitive area of about 40cm * 50cm), and heavier relatively (for example comprising the cellular collimator based on helical pitch), so the collision between detector head and the patient is a kind of risk.

For making up suitable shape track, the patient is placed on the subject support, and the radiologist uses manual controller to handle detector head with very near the patient.This is stored in the storer near (close-in) position (being sometimes referred to as " mark position "), and handles this detector head to another approximated position, this another approximated position provides patient's different angles or visual angle to define another mark position.Then the mark position of some such definition is carried out interpolation to make up suitable shape track.Such suitable shape trajectory planning must allow sufficient detector head to experimenter's gap so that margin of safety to be provided.

The optical proximity sensing system also is known.These systems use linear array of lasers or other directional light sources to define the sheet laser of the radiation sensitive face that is parallel to detector head.The continuity of the optical detector foil detector light source of relative orientation light source arrangement.When object and sheet laser intersect, be interrupted to the optical signalling of some optical detectors, thereby it is destroyed to indicate this sheet laser.In some are arranged, comprise the parallel plate light source of two spatial deviation.If it is destroyed that sheet laser does not all have, infer that then object is from must be also far.If a sheet laser is destroyed, infer that then object is in the target range scope.If two sheet lasers are all destroyed, infer that then object is too close, perhaps indicate upcoming collision.

This optical proximity sensing system usually from the radiation sensitive face of detector head to outer projection, this may be problematic.In addition, the degree of approach indication that is provided is dispersed.This degree of approach indication is a two-value under the situation of single sheet laser.For two sheet lasers, degree of approach indication is (zero, one or two sheet laser is destroyed) of three values.Can realize higher resolution, but cost is to comprise extra sheet laser.Resolution finally is subjected to the restriction of light scattering, diffraction or other blurring effects, and these blurring effects have limited the close degree of adjacent sheet light source.

In addition, one or more stationkeeping of one or more sheet lasers discrete degree of approach indication.The adjustment of degree of approach indication or impossible perhaps needs by manually or use suitable automated optical device to come the position of trimmer light source.If this adjustment is provided, it will increase the overall complexity of optical proximity sensing system.

In addition, existing optical proximity sensing system is not distinguished the type that object destroys sheet laser.Especially, sheet laser that clothes or bedding cause destroys and will be detected, thereby will be with respect to clothes or bedding rather than with respect to patient's position locator head.

The device and method of the novel improved that overcomes the problems referred to above and other problems hereinafter is provided.

According to an aspect, a kind of radiation detector head is disclosed, it comprises radiation sensitive face and a plurality of capacity cell, described radiation sensitive face is configured to probe radiation, and described a plurality of capacity cells are set on the described radiation sensitive face and are configured to detect the degree of approach of experimenter and described radiation sensitive face.

According on the other hand, a kind of gamma camera is disclosed, it comprises a plurality of radiation detector head.At least one radiation detector head comprises a plurality of capacity cells on the radiosensitive part that is arranged on described at least radiation detector head.Proximity sensor monitor and described a plurality of capacity cell are coupled so that detect the degree of approach of experimenter and described radiation detector head based on the measurement electrical characteristics of described capacity cell.

According on the other hand, utilize radiation detector head to carry out the image-forming data acquisition method, this radiation detector head comprises and is arranged at its lip-deep a plurality of capacity cells.This image-forming data acquisition method comprises: move described radiation detector head with respect to the experimenter; Gathering radiation data from described experimenter during described the moving or during the static interval between described the moving; During described moving, measure the electrical characteristics of described capacity cell; And based on the distance of measured electrical characteristics control detector head to the experimenter.

According on the other hand, a kind of gamma camera is disclosed, it comprises movably radiation detector head.At least one capacity cell is set on the described radiation detector head and comprises the spaced apart parallel current-carrying plate.Collision sensor monitor is configured to detect in response to the mechanically deform at the interval between the described plate conduction current that flows between described parallel conductive plates.

An advantage is to radiation detector head provides proximity sensor, and this proximity sensor provides continuous but not discrete degree of approach indication.

Another advantage is to provide to pillow or the insensitive proximity sensor of clothes, thus in medical application with respect to the patient but not with respect to patient's position locator heads such as clothes, pillow, sheet or other clothes.

Another advantage is to provide electric proximity sensor, and this electricity proximity sensor provides continuous range information and collision detection interlocking ability.

Another advantage is the electric proximity sensor that provides thin, and this thin electric proximity sensor has inapparent substantially outstanding from radiation-sensitive detector face.

The proximity sensor that another advantage is to obtain continuously the distance feedback with provide the scanner of data acquisition or controller combined, wherein detector head can change between the anatomic region between the patient, same patient or otherwise to patient's distance.

Another advantage is to provide the proximity sensor of substantitally planar, can utilize well-known lithographic plate patterning techniques to make up this proximity sensor.

Those skilled in the art will recognize more advantages of the present invention on the basis of reading and describing in detail below the understanding.

Fig. 1 diagrammatically illustrates the skeleton view of gamma camera;

Fig. 2 and 3 diagrammatically illustrates the skeleton view and the side cross-sectional, view of one of radiation detector head of the gamma camera of Fig. 1 respectively;

Fig. 4 diagrammatically illustrates the side cross-sectional, view of one of capacity cell on the side that is arranged on radiation detector head shown in Figure 2;

Fig. 5 diagrammatically illustrates suitable sample circuit;

Fig. 6 diagrammatically illustrates the proper signal treatment circuit that is used to handle the sampled signal that the sample circuit by Fig. 5 generates;

Fig. 7 diagrammatically illustrates suitable degree of approach control and the collision avoidance method of carrying out of system by Fig. 1-6;

Fig. 8 diagrammatically is illustrated in the degree of approach sensing measurement that whole body planar imaging data acquisition period is carried out;

Fig. 9 diagrammatically is illustrated in the degree of approach sensing that the tomographic imaging data acquisition period that is applicable to cardiac imaging carries out and measures;

Figure 10 A, 10B and 10C illustrate respective front, side view and the top view of the gamma camera with circular scan frame and two radiation detector head;

Figure 11 diagrammatically illustrates the skeleton view of one of radiation detector head of the gamma camera of Figure 10 A, 10B and 10C, comprises description that install previously and the capacity cell that install the side.

With reference to figure 1, a kind of nuclear medicine imaging system comprises gamma camera 8, illustrated in the explanation embodiment in this gamma camera comprise two radiation detector head 10,12.In other embodiments, this gamma camera can comprise one, two, three, four, five, six, seven or more a plurality of detector head.

Radiation detector head

10,12 has radiation

sensitive face

14,16 separately, and these radiation sensitive face generally are arranged to towards patient support or pallet 18.Illustrated in the

detector head

10,12 of explanation support by separately radial type multi-joint robotic arm 20,22.Each

robotic arm

20,22 comprises the controlled translation of electronics, rotate, turn or the combination of other mechanical joints, these mechanical joints are realized some freedoms of motion collaboratively or jointly, such as

detector head

10,12 towards patient bed 18 or away from patient bed 18 radial motion, these are perpendicular to the tangential motion on the direction of radial motion, and circular motion etc.The

robotic arm

20,22 that illustrates illustrated in each ends at forked

support member

24,26 respectively.Forked

support member

24,26 directly supports

detector head

10,12 respectively.

Camera electronics 30 provides the control to radial type

robotic arm

20,22, and transmitting power is given

robotic arm

20,22 and

detector head

10,12, and output is from the radiation detection information of detector head 10,12.Camera electronics 30 randomly is coupled with video monitor 32, so that show about the state of gamma camera 8 and the various information of operation.

Illustrated in the explanation the gamma camera 8 that comprises

radiation detector

10,12, patient support 18,

robotic arm

20,22, camera electronics 30 and video display 32 suitably be presented as Skylight ^TMNuclear camera (can obtain) from the Philips Medical Systems of Dutch Eindhoven.Yet, basically can put into practice detector head distance sensing disclosed herein and collision avoidance apparatuses and method by the gamma camera of any kind, the gamma camera of these types provides can fit shape ground around the patient or at the mobile one or more radiation detectors of patient on every side.For example, it can use together in conjunction with the gamma camera of the less detector head with bigger quantity.In certain embodiments, replace

robotic arm

20,22 with ring-type scanning support 20 ' (in the phantom of Fig. 1, the drawing) of supporting detector head 10,12.In these embodiments, thereby ring-type scanning support 20 ' comprise supports these rotatable scanning supports parts of 10,12 and makes that these 10,12 can be around bed 18 revolutions, and comprise provide detector head radially with the gamma detector head sectional fixture (not shown) of tangential motion.In ring-type scanning support or robotic arm mounting arrangements, the forked

support member

24,26 of explanation illustrated in can being different from the direct-connected terminal mounting structure of radiation detector head.For example, can wait with the one-sided hold-down arm of side that is positioned at detector head or back, the asymmetric arrangement that comprises some erection columns and replace forked support member 24,26.Gamma camera 8 also can comprise other features that are illustrated in Fig. 1 for simplicity and not, such as Skylight ^TMNuclear camera and the available autocollimator interchanger of some other gamma camera.

Continuation is with reference to figure 1, and camera electronics 30 comprises automation controller 34, this automation controller can be by hand controls 36 with operate in manual mode so that utilize

robotic arm

20,22 to handle detector heads 10,12.As an alternative, can utilize the suitable control algolithm that realizes by camera electronics 30 to operate automation controller 34, so that along predetermined suitable shape track 38 mobile detector heads 10,12.In certain embodiments, video monitor 32 can be configured to lasting " p scope " pattern output, its demonstrate with

detector

10,12 in the selected corresponding radiation detection figure of one detector face.Radiologist or other operators suitably use hand controls 36 and show in conjunction with " p scope ", the visual observation of the position of detector head or other feedbacks to be to determine some approximated positions of detector head, be mark position, can interpolation or construct suitable shape track 38 in addition according to these positions.

In order to gather the tomographic imaging data, automation controller 34 utilizes

robotic arm

20,22 to handle

detector head

10,12 so that substantially along suitable shape track 38 mobile detector heads 10,12.During this automatic orbit come and go to move,

detector head

10,12 was collected imaging datas, and this imaging data is stored in the imaging data storer 40.For example, this imaging data can be the data for projection under SPECT imaging situation, or the line of response data when under the PET imaging pattern, using gamma camera etc.Reconstruction processor 42 is used suitable reconstruction algorithm (such as through the backprojection reconstruction algorithm of filtering, iterative reconstruction algorithm etc.) and is calculated reconstructed image according to collected imaging data.This reconstructed image is stored in the video memory 44, and may be displayed on the display of user interface 46, perhaps be stored in electronic memory, magnetic store or the optical memory being used for and retrieve after a while, perhaps via LAN (Local Area Network) or Internet transmission, perhaps handle, perhaps otherwise utilize by the back reconstructed image.Illustrated in the explanation embodiment in, user interface 46 also provides the user interface with camera electronics 30.In other embodiments, replace user interface 46 or, can use video monitor 32, hand controls 36 or other user interface facilities so that the user interface with camera electronics 30 to be provided except user interface 46.

Continuation with reference to figure 1 and further referring to figs. 2 and 3, each

detector head

10,12 comprises the radiation sensitive face 50 of substantitally planar, this radiation sensitive face illustrated in comprise collimator 52 among the embodiment of explanation.Collimator 52 is collimators of pin hole, cellular or other types, and it is made and have the zone of the radiation transmitted of the pin hole, opening or the filling that the radiation that enters are collimated on substantially perpendicular to the direction of the radiation sensitive face 50 of substantitally planar by radiation-absorbing material.In other embodiments, can use the radiation collimation that the to enter strip type collimator in the plane.In another embodiment, if for example detector head is used to PET (positron emission tomography) (PET) imaging, then can omit collimator.Illustrated in

explanation detector head

10,12 each all also comprise radiation detector array 54.Illustrated in the radiation detector 54 of explanation comprise one or more scintillators 55, these one or more scintillators be arranged as a plurality of photomultipliers 56 optical coupled of observing these one or more scintillators 55.Photomultiplier 56 is randomly replaced by the optical sensor (such as photodiode array) of another type.The term " light " that is used to represent the flicker output of one or more scintillators 55 comprises visible light and sightless ultraviolet light or infrared light simultaneously.The output of photomultiplier 56 is imported into the electronic equipment that for example is arranged on the printed circuit board (PCB) 58.Replacement is based on the radiation detector 54 of scintillator, can use directly absorbed radiation and export electronic signal in response to this of a plurality of radio-sensitive elements (for example based on solid-state CZT detector).

Continuation is with reference to figure 1 and further with reference to figure 2-4, in the

detector head

10,12 one or two also comprises the degree of approach or distance sensing system, and this degree of approach or distance sensing system comprise a plurality of capacity cells 60 (Fig. 2,3 and 4), proximity sensor monitor 62 (Fig. 1) and collision sensor monitor 64 (Fig. 1).Illustrated in the explanation capacity cell 60 are planar capacitors, such as plane-parallel capacitor, each plane-parallel capacitor comprises that (referring to Fig. 3) is by air or isolated first and second parallel

conductive plates

66,67 of insulating material 68 (such as foamed material, dielectric material, epoxy resin etc.).If use capacity cell in the described herein conduction collision sense mode, then insulating material 68 should be arranged to have betwixt the isolated spacer elements of essence air gap, thereby make

plate

66,67 to be compressed and contact with each other, perhaps at least enough near so that conduction current can flow across the sept of mechanical compress.Therefore, in certain embodiments, sept is grid, array or other configuration of foam, dielectric material etc., and it has the essence separating area between sept, and parallel-plate can be compressed between sept together to realize collision sense.On the other hand,, capacity cell do not conduct electricity collision sense if only using under the capacitance sensing pattern, then can be current-carrying

plate

66,67 is spaced apart with the dielectric material of rigidity more, and this dielectric material is the abundant space between the filled

conductive plate

66,67 randomly.In addition, replace parallel plate planar capacitors, can use other configurations, such as plane capacitor sensor and nonplanar second conducting element.Also second conductor of collimator 52 as capacitor adopted in expection, although if collimator by electrical ground then it can not be used as the current-carrying plate of capacity cell.Illustrated among the embodiment of explanation, planar capacitor 60 is the plane-parallel capacitors with two current-

carrying plates

66,67, wherein base plate or lower plate 67 is spaced apart by insulating material 70 (such as foam or other dielectric layers) and collimator 52.In certain embodiments, insulating material 70 is arranged to have betwixt the grid or the array of the spacer elements of air gap.In suitable job operation, each all is arranged on conducting film (such as copper film) on the dielectric substrate of the substantitally planar that limits insulation course 68 parallel

conductive plates

66,67, wherein with conductive film patternization with the array that defines plane-parallel capacitor 60 and optional electrical interconnection trace.Illustrated in the explanation embodiment in, the pattern

conductive film

66,67 in an identical manner, thereby make each plane-parallel capacitor have the conductive

parallel plates

66,67 of basic identical size.In other contemplated embodiments, two conducting films of patterning are to provide the parallel-plate of different area by different way.Capacity cell 60 is arranged on the radiation sensitive face 50, randomly, is arranged on the enclosing cover 72 interior (this optional enclosing cover is schematically with dashed lines indication in Fig. 3) of radiation-sensitive face 50.Other elements of conductive

parallel plates

66,67, insulating material or

layer

68,70 or capacity cell 60 should be chosen as the decay of avoiding substantially by the radiation of scintillator 55 detections.

Additional capacitors element 76 additionally or alternately is arranged on a side of

radiation detector head

10,12 or the many sides to detect side proximity.By with particular reference to Fig. 4, illustrated in the explanation embodiment in, the capacity cell 76 that install the side is by

copper layer

78,80 is carried out the plane-parallel capacitor that patterning forms, these copper layers are laminated on the opposite side of epoxy resin board 82 of double-sided printed-circuit board, and this double-sided printed-circuit board is spaced apart with the side of collimator 54 by froth bed 84.Because by capacity cell 76 probe radiation of side installation, these elements are not randomly made by radiation-absorbing material.In this method, the epoxy resin board 82 of printed circuit board (PCB) limits parallel

conductive plates

78,80 isolated insulation courses.

Continue with reference to figure 1-4, proximity sensor monitor 62 is suitably measured the electrical characteristics of each

capacity cell

60,76, such as electric capacity, impedance or admittance.Electric conductor (such as human body, contain or carry the vein inner bag of fluid or pipe etc.) near will causing the electric capacity of nearest capacity cell to change, variable quantity depend on conductor near the degree or the quantitative degree of approach.Therefore, along with patient or other conductors move towards capacity cell or away from capacity cell, capacitance or other are measured electrical characteristics and will be changed.On the other hand, bedding or clothes are nonconducting, even therefore very near also only causing electric capacity that very little variation takes place or not changing.

In suitable measuring method, proximity sensor monitor 62 is applied to the specific plane-parallel capacitor of a plurality of

capacity cells

60,76 with ac signal or ac signal component, and detects the measurement electrical characteristics that generate in response to this.For example, in Fig. 2, by indicate the reciprocal grid sampling of capacity cell 60 by the raster path shown in the dotted line 90.The current capacity cell that is sampled is represented with the filled circles mark among Fig. 2.Proximity sensor monitor 62 is applied to the capacity cell of being represented by filled circles with ac signal or ac signal component, and utilize for example synchronous or coherent measurement commercial measurement response signal, should be synchronously or the coherent measurement technology for example be the United States Patent (USP) NO.4 of Satterwhite, 942, the technology of being discussed in 365 is incorporated the full content of this patent into this paper by reference.For example can be based on the impedance or the admittance of recently determining capacity cell of output signal phasor and input signal phasor.Randomly determine electric capacity according to this impedance or admittance, perhaps this impedance or admittance can be directly as measuring electrical characteristics.

In certain embodiments, proximity sensor monitor 62 also is configured to contiguous capacity cell (in Fig. 2 with the indication of open circles mark) is carried out bias voltage to reduce the influence of contiguous capacity cell to the measurement electrical characteristics of the capacity cell that is sampled (in Fig. 2 with the indication of filled circles mark).In alternative manner, the initial measurement of gathering the capacity cell that is sampled is to determine its voltage.Then contiguous capacity cell is driven into effectively another measured value that this voltage is also gathered the capacity cell that is sampled.Randomly repeat the measured value of the capacity cell that this process is sampled with further refinement.

Rule of thumb suitably definite measurement electrical characteristics as described below and detector head are to the relation between patient's the distance.Nearby do not have under experimenter's the situation initial value of measuring electrical characteristics is sampled to set up " infinity from " calibration point.At different detector heads to the additional sample of patient's distance collection to obtain calibration curve.Additionally or alternately, can determine to measure electrical characteristics and detector head by the first principle electrostatic calculations and arrive relation between patient's the distance.By using raster path 90 or another suitable sampling pattern that capacity cell 60 is carried out the grid sampling, can sample to all capacity cells 60 with the selected time interval (as per second or per ten seconds).The degree of approach suitably is defined as the smallest proximity of indicating by any capacity cell that is sampled 60.In addition, calculate proximity map in certain embodiments, wherein each proximity map element is the degree of approach of being measured by corresponding capacity cell.This proximity map for example can be used to discern detector head when move on it away from patient's direction (thereby robotic arm should begin towards patient's mobile detector head) and relatively detector head when on patient's direction, moving (thereby robotic arm should begin away from patient's mobile detector head) with it.

The accuracy that the degree of approach is measured area common and plane-

parallel capacitor

60,76 is inversely proportional to.On the other hand, littler plate area provides higher spatial resolution.In Fig. 2 and illustrative embodiment shown in Figure 3, plane-parallel capacitor 60 has the size of variation, and wherein the plate of maximum area is near the opposite edges of radiation sensitive face 50, and minimum plate is near the center of radiation sensitive face 50.Consider to select this layout based on cost and space.More capacity cell can increase the cost of preposition amplification or other function circuits, because the quantity of electronic unit and board area coverage rate are proportional with the quantity linearity of the capacity cell that is used for sensing usually.Yet, can select other layouts.For example, in some contemplated embodiments, use parallel plate capacitor element with all equivalent size.

The advantage of capacitive proximity sensing is that it is insensitive substantially to non-conducting material (such as bedding or clothing materials).Yet this advantage may be disadvantageous under the situation of the actual impact detector head of the nonconductor of relative stiffness.

Continue with reference to figure 1-4, collision sensor monitor 64 solves this problem by using the conduction current information from plane-parallel capacitor 60,76.In incorporating some embodiment of collision sensor monitor 64 into, insulation course 68 is made by deformable or submissive material, this deformable or submissive material can be compressed distortion so that

plate

66,67 contacts or be at least fully approaching, thereby allow conduction current to flow between these plates.Under suitable bias voltage from collision sensor monitor 64, therefore conduction current will flow between parallel

conductive plates

66,67 in response to the compression deformation of submissive material 68, and the compression deformation of submissive material 68 allows parallel

conductive plates

66,67 to contact with each other or reaches the degree of approach of fully pressing close to each other to produce the conduction shunting.Therefore, plane-parallel capacitor 60 and collision sensor monitor 64 define the binary switch of collision detection.Different with proximity detection, collision detection depends on the mechanically deform of submissive insulation course, therefore no matter collision body be conduction or electrical isolation can collision detection.

In Fig. 1, proximity sensor monitor 62 and collision sensor monitor 64 are depicted as separated components.In certain embodiments, these two parts can integrate partly or integrally.For example, single sensor monitor can apply the signal to the capacitor of current sensing, and this signal comprises the AC bias of Dc bias and stack.DC bias component is used to monitor the conduction current of indication collision, and the AC bias component is used for degree of approach sensing.As an alternative, AC compounent be can only use, and the impedance and the admittance of plural form measured.The impedance of plural form or the real part of admittance indication conduction current, and the imaginary part of the impedance of plural form or admittance is applicable to degree of approach sensing.

With reference to figure 5, graphic schematic electric sample circuit is shown, it is suitable for capacity cell 60 is sampled.Switch S 1, S2 are mainly used in and carry out grid scanning.Only have a front sensor plates 66 to be connected to sensing signal sometime, and the front sensor plates 66 of other capacity cells 60 of array is forced the current potential identical with survey sensor plate 66.This has reduced the possibility by the measurement distortion that contiguous capacity cell caused that influences field wire.Collision detection and switch S 1, that how S2 is provided with is irrelevant.On the contrary, when any

plate

66,67 of any at any time capacity cell 60 contacts with each other, all have conduction current to flow through diode DC and the line that is designated " collision alarm ", and this conduction current is read as the indication of collision.

Continuation is with reference to figure 5, and degree of approach sensing moves as follows.Pure oscillator (the 5V of 100KHz _Pp) be connected with header board 66 (being also referred to as sensor or sensory panel), by sensing signal line header board is measured.This connection causes front sensor plates 66 emission electric fields, and this electric field passes optional protective cover 72 and air and propagates towards near any object that is in different potentials.As shown in Figure 5; by the protecting component capacitor board 67 of sensory panel 66 back before via unity gain amplifier B sensor input signal being fed back to and via being provided with of switch S 1, S2 sensor input signal is fed back to contiguous protecting component, on the direction of object, this electric field is carried out bias voltage.Because have the strong capacitive coupling, contiguous front sensor plates 66 also remains on the guard signal level and transfers to contiguous header board 66 to prevent field wire from measured sensory panel 66.The prime amplifier A that is connected with measured sensory panel 66 has high input impedance, and this causes being approximately input capacitance C to the input voltage of this amplifier _In(be expressed as C herein with the electric capacity of the object of sensory panel 66 fronts _Obj) between dividing potential drop.With input capacitance C _InBe chosen as the electric capacity that approximates greatly when not having approaching object around the sensing element.In certain embodiments, with C _InBe set to about 1.5pF, although can use other values.The result is at the 2.5V of the input of prime amplifier A when not having approaching object _PpSignal.Along with object moves closer to sensory panel 66, increase near the electric capacity of object, this cause prime amplifier A place than low input-signal.By making big ground connection object, can be implemented in the lowest signal of hundreds of mV of the input of prime amplifier A near sensory panel 66 (for example almost the optional protective cover 72 of contact).

Unshowned in Fig. 5 is single order Hi-pass filter at the input stage place of each prime amplifier A, and this single order Hi-pass filter stops makes these amplifiers saturated from the 50Hz of electrical equipment or the noise of 60Hz.In certain embodiments, the 3dB cutoff frequency of this wave filter is about 3kHz.

The robustness of system is enough to resist the inefficacy of one or several capacity cell 60.For example, if disconnect to the electric wire of sensing element 66, then will C can not take place _ObjWith C _InBetween dividing potential drop, and input amplifier A will run into whole 5V _PpSignal.This is higher than any normal range of operation near object, so proximity sensor monitor 62 generation error message or handle in addition wrong reading suitably.If the electric wire to protecting component 67 disconnects, then guard signal will be followed the current potential of the collimator 52 of protection sensor 67 back, and this collimator is ground connection in this embodiment.This will produce the input signal of prime amplifier A, and this input signal is lower than any normal range of operation near object.Proximity sensor monitor 62 generation error message or handle in addition wrong reading suitably in this case.The sensory panel 66 of capacity cell 60 and fender 67 short circuits during colliding.Because see that from the visual angle of DC fender 67 is connected to-5V, this allows conduction current through diode DC, drives collision alarm then.The adjunct circuit of not shown this conduction current of processing of Fig. 5, but comparer and opener telegraph circuit can suitably be used.

With reference to figure 6, the microprocessor that it has been described synchroprobe or analog to digital converter and has comprised the firmware that is used for computed range and compensating gain and offset error.The circuit of Fig. 6 receives " sensing signal " and utilizes high pass (" HP ") filters H PF to carry out high-pass filtering, utilize synchronous demodulation piece SYNCH and the square wave input that is in 0 ° and 90 ° phase place to carry out synchronous demodulation, utilize low pass (" the LP ") filtering of low-pass filter LPF execution through the signal of demodulation, and carry out optional further signal Processing, such as analog to digital conversion, root mean square (RMS) or other average computation, gain calibration, offset correction etc. (in Fig. 6, indicating) with impact damper BUF diagram.The output of suitably being used impact damper BUF by proximity sensor monitor 62 is to determine the degree of approach.

So that under the situation of practice, make up a radiation detector head, this radiation detector head comprises 54 plane-parallel capacitors of 6 * 9 arrays of the area of crossing over radiation sensitive face in actual reduction.The area of these capacitors is similar to shown in Fig. 2 and 3 and changes, and wherein the capacitor of maximum area is 9 * 9cm ², the capacitor of minimum area is 9 * 3cm ²These capacitors are that the patterning copper sheet by 7 micron thickness forms, and the foam strip that these copper sheets are wide by 5mm, 1.6mm is high is spaced apart, and these foam strips distribute across cap surface in the place that separates about 10cm.Therefore, the space between the copper sheet mainly is an air, and this helps collision sense uses, wherein two sheets by mechanical compress together to generate conductive electrical current signal.Similar arrangement with the isolated foam strip of 10cm is used to the conductive layer of the bottom is separated with collimator.Plastic outer cover is placed on the array of capacitors that is arranged on the radiation sensitive face.The configuration electronic equipment is so that carry out a grid sampling of taking turns 54 capacity cells in about 1 millisecond, thereby makes whole detector can per second measure about 16 times of the distance of object.In actual reduction so as the practice situation under, make the side capacity cell by the conductive layer patternization that makes double-sided printed-circuit board.By providing side collision to detect to monitoring to the conduction current on ground via the L shaped carriage that is connected to the collimator framework from the trace on the printed circuit board (PCB) rear side.

Illustrated in the explanation embodiment comprise degree of approach sensing function and collision detection capabilities.Yet expection only comprises in these abilities one or another in given embodiment.For example, but detector head can omit degree of approach sensing function comprise the collision detection aspect, thereby provides safety interlock to bother or patient harm or defective detector head preventing.On the contrary, but detector head can comprise degree of approach sensing function omit collision detection capabilities.In one embodiment of back, can provide crash protection corresponding to conductor to avoid making

detector head

10,12 move closelyer to experimenter's distance by interlocking automation controller 34 than selected minimum detector head.

Illustrated in the capacity cell the 60, the 76th of explanation, have the planar capacitor of current-carrying plate 66, these current-carrying plates distribute across radiation sensitive face and with the radiation sensitive face parallel alignment.This provides the proximity detector of low profile, and it only extends short distance away from radiation sensitive face 50.For example, being simplified so that the embodiment that puts into practice comprises thickness is that the gross thickness of thickness gained of 1.6 millimeters (at thick froth beds) two 17 microns (0.017 millimeters) adding the patterning copper sheet is less than 2 millimeters plane-parallel capacitor.More generally, capacity cell randomly from radiation sensitive face 50 extensions less than 5 millimeters, thereby make proximity detector self do not introduce between radiation sensitive face 50 and the experimenter the line bonus of not expecting from.

The capacitive proximity sensing system is applicable to the workflow of simplifying the SPECT image-forming data acquisition.Be used for a kind of method of tomographic imaging, radiologist or other operators select start angle and the detector orientation expected, and order this system to begin one's study.Automatically

mobile detector head

10,12 is to the initial orientation angle of expectation for

automation executor

20,22, and the radius that reduces them lentamente is up to utilizing the capacitive proximity sensing to detect the separation of the detector of expectation to the patient.When carrying out the image-forming data acquisition end in each orientation,

automation executor

20,22

mobile detector heads

10,12 are away from patient's one small distance, so that redirect

detector head

10,12 at next orientation.Utilize the capacitive proximity sensing with position patient once more, and will reduce the distance that expires and hope at interval.Repeat this process at each position angle.Because range observation is continuous, the operator can select the distance expected, and also can select to increase or reduce this distance in research process.

The capacity cell 76 that install the side is installed on the leading edge and trailing edge of detector head 10,12.These are applicable to that for example the whole body planar imaging is used.In this research,

detector head

10,12 above the flat patient who crouches or below, and along patient's body from top to bottom (or to the end) from pin move.Along with

detector head

10,12 moves along patient's body, they suitably raise or reduce anatomical structure to avoid contact height to change, such as chest, belly, foot etc.In this planar scan application, the capacity cell 76 that install the side is measured detector distance before along body axes, thereby avoids higher object to allow sufficient time rising detector head.In certain embodiments, operator's workflow is as follows: select initial distance and stop distance with the indication overall scan length, and order gamma camera 8 begins to gather imaging data.Relative angle and the table start position of using the capacitive proximity sensing to come to determine automatically each detector head reduce detector radius to the desired distance apart from the patient, begin then to gather.

Even under the sight of quiescent imaging data acquisition, this moment is irrelevant with the detector orientation of automatic control, and the capacitive proximity sensing also helps the operator.Because the capacity cell 76 that install the side can detect the object before detector head, they can hand controls operating period of

automation executor

20,22 use with locate these 10,12.When the degree of approach that detects with the experimenter, slow down suitably that head moves and with stop head before the experimenter contacts and move.The collision sense ability can be as the secondary fail-safe device during the detector head location of this hand controls operation.

With reference to figure 7, suitable degree of approach control and the collision avoidance method carried out in conjunction with

capacity cell

60,67 by

monitor

62,64 have been described.In grid operation 100, proximity sensor monitor 62 for example utilizes raster path 90 (shown in Figure 2) or another suitable sampling pattern to come

sampling capacitance element

60,76 in succession.Grid operation 100 is measured each and is sampled the electrical characteristics of capacity cell, such as the electric capacity of measuring, admittance, impedance etc.In computation process 102, arrive experimenter's distance for each capacity cell computing element based on the electrical characteristics of measuring of each capacity cell.Computation process 104 determines that to experimenter's distance detector head arrives experimenter's distance according to each element.In the embodiment of Fig. 7, computation process 104 is chosen minimum element arrives the experimenter as detector head to experimenter's distance distance.This method can reduce the possibility of too high estimation detector head to experimenter's distance, and this can help security.Yet, computation process 104 can be used other formula, for example gets the experimenter is provided with the element that provides some robustnesss to avoid transient error to the average (wherein N is selected integer) of experimenter's distance N minimum element range observation or capacity cell out of order or that lost efficacy.Similarly, computation process 104 can be incorporated the filtering exceptional value into.For example, exceptional value can be identified as measure with the distance of the element of measuring at contiguous capacity cell to the extremely different element of experimenter's distance to the experimenter.

Continuation is with reference to figure 7, thereby 106 pairs of suitable robotic arms of

control operation

20,22 are operated to adjust the location match settings point distance 108 of detector head 10,12.Can generate this sctpoint distance 108 in every way.In certain embodiments, sctpoint distance 108 is constant distances, based on keeping less detector head to select this constant distance to the demand of experimenter's distance during the mechanical tolerance of gamma camera 8 and the imaging.Other factors also can randomly be incorporated sctpoint distance 108 into, such as the consideration item (for example, if patient information 110 indication patients have claustrophobia, then can select bigger sctpoint distance 108) about the patient.Another factor that can randomly incorporate into is a scan type information 112.For example,, then compare, can select less sctpoint distance 108 with the radioisotopic scanning of using higher signal strength (or higher dosage) if should scan the radioactive isotope that uses low signal intensity (or low dosage).Scan type information 112 also can be used to select sctpoint distance 108 with the balance between the demand of the high resolving power that reflects patient's comfort level and performed scan type or excellent picture quality.If scan type is the research of two parts (or more parts), for example the different time during studying uses two kinds of different isotopes, then can during studying, change sctpoint distance 108 in time, so that mobile detector head more closely when the isotope that uses than low signal for example.For tomographic scan, can adjust sctpoint distance 108 based on position, angle or azimuth position, so that for example when area-of-interest mobile detector relatively more closely during more away from radiation detector head.

As another illustrative factor, can consider anatomical region information 114, wherein,, also change sctpoint distance 108 so that different anatomic regions is carried out imaging even in same image scanning.For example, in head-to-toe swept-volume, with the imaging of carrying out of relative less head zone is compared, set point 108 can be set to lower (littler detector head is to experimenter's distance) when torso area relatively large and that comprise crucial anatomical features is carried out imaging.Relatively large detector head can also be applicable to head zone to experimenter's distance, is that this may make the patient feel under the weather because this imaging is placed in patient's facial front with detector head.Factor the 110,112, the 114th, illustrated examples it is also conceivable that additional in determining the process of set point 108 or other factors, such as radiologist's individual preference, management rules or best medical practice rule etc.

Continuation is with reference to figure 7, and collision avoidance system is also advantageously moved during imaging.During grid operation 100,, check 120 to whether detecting conduction current along with each capacity cell is sampled.If detect this conduction current by collision sensor monitor 64 (see figure 1)s, then start suitable collision sequence 122.This collision sequence can comprise all motions of for example causing the sense of hearing and/or visual alarm,

stop detector head

10,12 or

detector head

10,12 be returned to home away from the patient etc.

With reference to figure 8, show the position of the

detector head

10,12 that is used for the collection of whole body panel data.In Fig. 8, diagrammatically indicate the patient by the ellipse of representing head H, trunk T, arm A, shank L and the F of foot.This patient lies low on patient support or pallet 18 (indication diagrammatically in Fig. 8).Two

radiation detectors

10,12 respectively above patient body and below.The capacitance sensor array of top detector 10 is used for measuring the distance (measured distance in transit 8 usefulness arrows diagrammatically indicate) of immediate detector head to the patient.Then this measured value is used as the reference signal of dynamic vertical position locator, thereby realizes the specified gap between array and the patient.If pallet 18 conducts electricity, then the capacitance sensor array of bottomside sounding device 12 also randomly is used for moving along with detector head 12 and keeps the constant distance of detector head to pallet.As an alternative, suppose that pallet 18 has even and straight substantially profile, then can not have mobile bottomside sounding device head 12 under the situation of this FEEDBACK CONTROL.

In the whole body planar imaging data acquisition of Fig. 8,

detector

10,12 is along patient's body (as shown in Figure 8) or move to the end from pin from top to bottom.For example, in the head-to-toe image data acquiring of Fig. 8, illustrated in explanation detector position 10 ', 12 ' respectively indicate head-to-toe adopting to concentrate on the position of the

detector head

10,12 of time after a while.Therefore, advantageously that edge capacitance element 76 is so directed, promptly their measure the distance at detector head 10 " before ", so that the on the horizon outside variation of sensing patient's profile F of foot shown in Figure 8.This provides the detector 10 that raises of extra time for system, thereby avoids contacting with foot 10, still keeps the gap of the detector of expectation to the patient simultaneously as much as possible.

With reference to figure 9, in the cardiac imaging data acquisition,

detector

10,12 is relative to each other with 90 ° relative angle orientation.In Fig. 9, utilize and show patient's view of looking down from patient's head as the representative ellipse that Fig. 8 indicated, wherein add the oval belly B that indicates the patient of part.For the heart collection,

detector head

10,12 should be as far as possible near the patient with optimize image quality.Therefore, the nearest proximity value that is provided by any capacity cell 60 is used as the guiding proximity signal of position locator.In heart was gathered, two

detector heads

10,12 near degree of approach relative to each other was to make the problem complicated factors.If the detected nearest degree of approach is actually with respect to another detector head rather than with respect to the patient, then may provide wrong degree of approach information.For addressing this problem, two

detector heads

10,12 are arranged as master control head and driven head respectively and are configured to synchronized with each otherly in certain embodiments, and the grid sequence on the radiation sensitive face of one of them radiation detector head becomes mirror image with grid sequence on the radiation sensitive face of another radiation detector head.As described in reference to figure 6, by carrying out skew and gain calibration, between

detector

10,12, do not have under the situation of object, each detector head can be cancelled the influence of another detector head.In the embodiment shown in fig. 9, grid sequence commencing signal is superimposed upon from the lid of master detector head 10 and sends on the signal 130 of 100KHz of driven detector head 12.

In the heart of Fig. 9 is gathered, perhaps be positioned in patient's the tomographic acquisition example (not shown) of opposite side at two detector heads, patient's imaging data is gathered at the place at a lot of position angle, therefore advantageously provides the measured value of detector head to the renewal of patient's distance in each place, position angle proximity sensor system.Because human body is irregular shape, by each new position angle, different one or one group of plane-parallel capacitor 60 will provide the measured value of " the most approaching " usually.Therefore, the measured value of the sampling of the grid by all plane-parallel capacitors 60 " the most approaching " of being gathered is suitable for use as the distance of minimum detector head to the patient.

With reference to figure 10A, 10B, 10C and 11, illustrate another embodiment.Figure 10 A, 10B and 10C show respective front, side view and the top view of gamma camera 180, this gamma camera 180 comprises two detector heads 210,212 that are installed on the automation executor 220,222, automation executor 220,222 and then be installed on the circular scan frame 224.Illustrated among the embodiment of explanation, two detector heads 210,212 are orientated as with 180 ° position angle separate, thereby be applicable to tomographic acquisition or be applicable to that plane as shown in Figure 8 gathers.By centering on the position angle of circular scan frame 224 (not shown in Figure 10 A, 10B and 10C) with a detector head and automation executor half-twist thereof, can be so that the heart collection of detector head execution graph 9.Figure 11 shows one skeleton view in the radiation detector head 210,212.This detector head comprises 54 front proximity sense capacitance elements 260, and these capacity cells are arranged to be distributed on the radiation sensitive face and basic 6 * 9 grids that cover radiation sensitive face.Be similar to shown in Figure 2ly, the area of capacity cell 260 changes across radiation sensitive face.In addition, show four side proximity sense capacitance elements 276 on the side of detector head 210,212.Degree of approach sense capacitance element 260 is suitably disposed in the configuration that is similar to the degree of approach sense capacitance element of having described 60, and degree of approach sense capacitance element 276 is suitably disposed in the configuration that is similar to the degree of approach sense capacitance element of having described 76 simultaneously.Therefore, degree of approach sense capacitance element 260,276 is applicable to degree of approach sensing and collision detection.

By having described the present invention with reference to preferred embodiment.Reading and understanding on the basis of preceding detailed description, other staff can make amendment and change.The invention is intended to be read as and comprise all such modifications and variation, as long as they are in the scope of appended claim and equivalent thereof.

Claims

1, a kind of radiation detector head (10,12,210,212) comprising:

Radiation sensitive face (50), it is configured to probe radiation; With

A plurality of capacity cells (60,260), it is set on the described radiation sensitive face and is configured to detect the degree of approach of experimenter and described radiation sensitive face.

2, radiation detector head as claimed in claim 1 (10,12,210,212), wherein, described radiation sensitive face (50) comprising:

Radiation collimation instrument (52); With

Radiation detector array (54), it is arranged in radiation through surveying described radiation after the described radiation collimation instrument.

3, radiation detector head as claimed in claim 2 (10,12,210,212), wherein, it is one of following that described radiation detector array (54) comprises:

(i) one or more scintillators (55), its be arranged as a plurality of optical sensors (56) optical coupled of observing described one or more scintillators and

(ii) a plurality of radio-sensitive elements, it is configured to absorbed radiation and exports electric signal in response to this.

4, radiation detector head as claimed in claim 1 (10,12,210,212), wherein, described sensitive surface (50) is a substantitally planar, and described a plurality of capacity cell (60,260) comprising:

Current-carrying plate array (66), its distribute across described radiation sensitive face and with described radiation sensitive face parallel alignment.

5, radiation detector head as claimed in claim 4 (10,12,210,212), wherein, described radiation sensitive face (50) comprising:

Radiation collimation instrument (52), it is arranged to along the direction of cardinal principle perpendicular to the sensitive surface of described substantitally planar radiation is collimated; With

6, radiation detector head as claimed in claim 4 (10,12,210,212), wherein, described current-carrying plate array (66) is sampled to the electrical characteristics that are associated with each capacitor board with support by electrical interconnection.

7, radiation detector head (10 as claimed in claim 6,12,210,212), wherein, described a plurality of capacity cells (60,260) also comprise spaced apart parallel current-carrying plate (66,67), described parallel conductive plates limits a plurality of plane-parallel capacitors that distribute across described radiation sensitive face, and the electrical characteristics of being sampled comprise in response to in the described parallel conductive plates at least one force of compression and the conduction current that between described parallel conductive plates, flows.

8, radiation detector head as claimed in claim 7 (10,12,210,212), wherein, the electrical characteristics of being sampled also comprise electric capacity, admittance or the impedance of each plane-parallel capacitor (60,260).

9, radiation detector head as claimed in claim 6 (10,12,210,212), wherein, the electrical characteristics of being sampled comprise the ac signal of the current-carrying plate (66) of sampling to putting on or the response of ac signal component.

10, radiation detector head as claimed in claim 4 (10,12,210,212), wherein, described current-carrying plate array (66) comprising:

Conducting film (66), it is patterned to define described current-carrying plate array.

11, radiation detector head as claimed in claim 4 (10,12,210,212), wherein, described a plurality of capacity cells (60,260) also comprise:

Second conducting film (67), itself and described conducting film (66) are spaced apart.

12, radiation detector head as claimed in claim 11 (10,12,210,212), wherein, described second conducting film (67) thus be patterned and make that each capacity cell is the plane-parallel capacitor with conductive parallel plates of basic identical size.

13, radiation detector head (10 as claimed in claim 4,12,210,212), wherein, be positioned near the area of current-carrying plate of the described current-carrying plate array (66) the center of described radiation sensitive face (50) substantially less than near the area of at least some current-carrying plates the edge that is positioned at described radiation sensitive face.

14, radiation detector head as claimed in claim 1 (10,12,210,212), wherein, described radiation sensitive face (50) is a substantitally planar, and described a plurality of capacity cell (60,260) extends less than 5 millimeters from the sensitive surface (50) of described substantitally planar.

15, radiation detector head as claimed in claim 1 (10,12,210,212) also comprises:

One or more capacity cells (76,276), it is set at the side of described radiation detector head, and is configured to detect the degree of approach with the described side of described radiation detector head.

16, radiation detector head as claimed in claim 1 (10,12,210,212) also comprises:

Enclosing cover (72), it is set on the described radiation sensitive face (50) and on the described a plurality of capacity cells (60,260) that are arranged on the described radiation sensitive face.

17, a kind of gamma camera (8,180), it comprises:

A plurality of radiation detector head (10,12,210,212), at least one radiation detector head comprise a plurality of capacity cells (60,260,76,276) on the radiosensitive part (50) that is arranged on described at least radiation detector head; With

Proximity sensor monitor (62), itself and described a plurality of capacity cell are coupled so that detect the degree of approach of experimenter and described radiation detector head based on the measurement electrical characteristics of described capacity cell.

18, gamma camera (8 as claimed in claim 17,180), wherein, described proximity sensor monitor (62) is configured to sample in succession each capacity cell in described a plurality of capacity cell (60,260) to detect the measurement electrical characteristics that generated by described capacity cell.

19, gamma camera (8 as claimed in claim 18,180), wherein, described proximity sensor monitor (62) also is configured to carrying out bias voltage with the influence to measured electrical characteristics of the capacity cell that reduces described vicinity with the contiguous capacity cell of the capacity cell of being sampled.

20, gamma camera (8 as claimed in claim 17,180), wherein, described a plurality of capacity cell (60,260,76,276) comprise isolated current-carrying plate (66,67), and described proximity sensor monitor (62) be configured to detect by compression and reduce or conduction current between the described current-carrying plate that the gap between the described isolated current-carrying plate produces is eliminated in compression.

21, a kind of image-forming data acquisition method of utilizing radiation detector head (10,12,210,212) to carry out, described radiation detector head comprise and are arranged on its lip-deep a plurality of capacity cells (60,260,76,276) that described image-forming data acquisition method comprises:

Move described radiation detector head with respect to the experimenter;

Utilizing described radiation detector head to gather radiation data during described the moving or during the static interval between described the moving from described experimenter;

During described moving, measure the electrical characteristics of described capacity cell; And

Based on the distance of measured electrical characteristics control detector head to the experimenter.

22, image-forming data acquisition method as claimed in claim 21 wherein, describedly is controlled at that whole described to keep described detector head during moving and gathering be a steady state value to experimenter's distance.

23, image-forming data acquisition method as claimed in claim 21, wherein, automation controller 34 changes the distance of described detector head to the experimenter according to nearest anatomic region during described moving.

24, image-forming data acquisition method as claimed in claim 21, wherein, it is sctpoint distance (108) to experimenter's distance that described detector head is kept in described control.

25, image-forming data acquisition method as claimed in claim 24, wherein, determine described sctpoint distance (108) based at least one in patient information (110), scan type information (112), anatomical region information (114) and radiologist's the individual preference.

26, image-forming data acquisition method as claimed in claim 24, wherein, described move and gather during described sctpoint distance (108) change once at least.

27, image-forming data acquisition method as claimed in claim 21, wherein, the described measurement electrical characteristics that are controlled to small part based on the described experimenter's of indication part on the horizon, described electrical characteristics are to utilize to be arranged on described detector head (10,12,210,212) capacity cell on the leading edge (76,276) is measured.

28, a kind of gamma camera (8,180), it comprises:

Radiation detector head (10,12,210,212) movably;

At least one capacity cell (60,260), it is arranged on the described radiation detector head and comprises spaced apart parallel current-carrying plate (66,67); And

Collision sensor monitor (64), it is configured to detect in response to the mechanically deform at the interval between the described plate conduction current that flows between described parallel conductive plates.